diff --git a/pkgs/development/ocaml-modules/rdbg/default.nix b/pkgs/development/ocaml-modules/rdbg/default.nix
index ba7e71136957..dcb2a438fd4b 100644
--- a/pkgs/development/ocaml-modules/rdbg/default.nix
+++ b/pkgs/development/ocaml-modules/rdbg/default.nix
@@ -8,7 +8,7 @@
   ounit,
 }:
 
-buildDunePackage rec {
+buildDunePackage (finalAttrs: {
   pname = "rdbg";
   version = "1.199.0";
 
@@ -24,7 +24,7 @@ buildDunePackage rec {
       };
 
   src = fetchurl {
-    url = "https://www-verimag.imag.fr/DIST-TOOLS/SYNCHRONE/pool/rdbg.v${version}.tgz";
+    url = "https://www-verimag.imag.fr/DIST-TOOLS/SYNCHRONE/pool/rdbg.v${finalAttrs.version}.tgz";
     hash = "sha512:6076eaa3608a313f8ac71a4f5aa4fcc64aeb0c646d581e5035110d4c80f94de34f2ba26f90a9a1e92a7f788c9e799f1f7b0e3728c853a21983ad732f0ee60352";
   };
 
@@ -43,4 +43,4 @@ buildDunePackage rec {
     license = lib.licenses.cecill21;
     maintainers = [ lib.maintainers.delta ];
   };
-}
+})